Field of the Invention
Embodiments relate to diaphragm-based solution pumps for moving liquids. More particularly, embodiments relate to solutions pumps for refrigeration systems that are configured to self-prime.
Description of the Related Art
Many different types of systems rely upon solution pumps to move liquids from one part of an apparatus to another. For example, liquid/vapor absorption systems often utilize absorber heat exchange or generator/absorber heat exchange (GAX) cycles for supplying cooling, and heating to an indoor coil and other heat exchange components exposed to the space or load to be conditioned. In these types of apparatus, a solution pump is often used to pump ammonia-rich absorption fluid from the absorber assembly to the generator assembly. This process maintains pressure differentials between the low pressure, absorber side and the high pressure, generator side of the absorption system apparatus. An example of aqua-ammonia an absorption heat pumps using GAX cycles is disclosed in U.S. Pat. No. 6,705,111.
Some solution pumps use a diaphragm for pumping liquid and typically rely on increasing and decreasing the pressure exerted on a diaphragm to change the volume within a pump chamber. In some embodiments of a hydraulic diaphragm pump, a piston is configured to move oil against the diaphragm so that increased pressure from the piston pushes the diaphragm in one direction, while atmospheric pressure or spring pressure on the oil returns the diaphragm to its starting position. This results in a cycling operation of the pump and fluid movement into and out of check valves linked to the pump chamber. Although such pumps function adequately where the system is primed, they do not generate enough suction to be self-priming. Thus, when there is no fluid present in the solution chamber at start up, such presently used hydraulic diaphragm pumps may not perform adequately.